I saw my sister in laws body

My sister in law came to stay the weekend with us last week and as the night was winding down my sister in law went for a shower and my wife asked me to water the flower bed, I went out through the garage and the basement bedroom window is a couple feet to the side of the garage door that accesses the back yard, Right under our bedroom window, I went into the back and watered all the flower beds and when I returned to the garage, I didn't think anything of it but as I rounded the corner of the house I noticed the light on in the spare bedroom downstairs, As I passed I glance down and there was my wifes little sister standing in just a towel going through her suit case.I passed the window but curiosity got the better of me and I stopped, Stepped back and looked into the window stood there and watched as she turned her back to the window and pulled her towel off, She has always been a very pretty girl, Tall, slim, large b****, dark hair, beautiful, sparkly, Green eyes, She bent over wrapping her hair in the towel, My heart stopped, She has a tiny, firm looking little ass and then it happened, She turned to face the window and I saw her entire body...Oh my god, 20 years old and amazing.I love my wife and think she is a sexy woman but WOW, she has never had a body like that, I have never seen b**** that big that stood up firm and perfect as hers, Areolae that were small for the size of her bobs, Light pink with light pink nipples, Freckled cleavage, Flat stomach, Perfectly bald p****, Long, smooth legs, She took her towel off after fluffing her hair, Her b**** barely even moved they are so firm, She laid her towel on the bed, Sat on it and grabbed a tube of lotion, I knelt there watching her as she put lotion on her legs, When she was done she leaned forward, Spread her legs and looked at her p****, As she did I got a full look at it, Perfect, pink and bald, No lips hanging out absolutely perfect, it was onl a couple seconds but I seen it, She stood up and I watched her put lotion on her stomach and as she rubbed it on her b**** they jiggled a bit but are so firm I didn't even think girls actually had b**** that big that were still firm, I am still in awe of her b****, I watched her stand naked in front of the mirror and brush her hair then she crawled onto the bed and sat against the head board with her knees up and opened her ipad, I watched her for about 15 minutes just sitting there, I couldn't see what she was looking at but I could see her perfect b**** and long sexy legs, When she was done she closed it and put it on the bed, Got up and I watched as she bent over, Stepped into a sexy little pair of shorts, Stood up, faced the window and pulled a tank top over her head and down over her big b****, As she reached for the light switch I stepped away from the window.I went into the garage, I went inside and my wife was in bed, She looked at me and said "What took so long", I said "Oh, I was just fixing the spray nozzle", She pulled the covers down to show she was topless, I was still hard and whipped off my clothes, I got on top of her and only lasted about five minutes, Luckily she didn't get off so she went down on me and I was hard again in about a minute, She looked at me and said "Hmmm, Somebody is excited tonight", I threw her on her back and managed to last until she finished but just barely.We laid there breathing heavy and she said "What got into you", I just smiled and kissed her, I cant believe how amazing her sisters body is and hope I get another chance to see it again sometime.